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At least 757 records · Page 42Linked to original sources
PubMed2004

Species-specific calls evoke asymmetric activity in the monkey's temporal poles.

It has often been proposed that the vocal calls of monkeys are precursors of human speech, in part because they provide critical information to other members of the species who rely on them for survival and social interactions. Both behavioural and lesion studies suggest that monkeys, like humans, use the auditory system of the left hemisphere preferentially to process vocalizations. To investigate the pattern of neural activity that might underlie this particular form of functional asymmetry in monkeys, we measured local cerebral metabolic activity while the animals listened passively to species-specific calls compared with a variety of other classes of sound. Within the superior temporal gyrus, significantly greater metabolic activity occurred on the left side than on the right, only in the region of the temporal pole and only in response to monkey calls. This functional asymmetry was absent when these regions were separated by forebrain commissurotomy, suggesting that the perception of vocalizations elicits concurrent interhemispheric interactions that focus the auditory processing within a specialized area of one hemisphere.

Acoustic Stimulation↗
PubMed2005

Albedo of the south pole on Mars determined by topographic forcing of atmosphere dynamics.

The nature of the martian south polar cap has remained enigmatic since the first spacecraft observations. In particular, the presence of a perennial carbon dioxide ice cap, the formation of a vast area of black 'slab ice' known as the Cryptic region and the asymmetric springtime retreat of the cap have eluded explanation. Here we present observations and climate modelling that indicate the south pole of Mars is characterized by two distinct regional climates that are the result of dynamical forcing by the largest southern impact basins, Argyre and Hellas. The style of surface frost deposition is controlled by these regional climates. In the cold and stormy conditions that exist poleward of 60 degrees S and extend 180 degrees in longitude west from the Mountains of Mitchel (approximately 30 degrees W), surface frost accumulation is dominated by precipitation. In the opposite hemisphere, the polar atmosphere is relatively warm and clear and frost accumulation is dominated by direct vapour deposition. It is the differences in these deposition styles that determine the cap albedo.

Journal Article↗
PubMed2006

Regulation of cytokinesis by spindle-pole bodies.

In the fission yeast Schizosaccharomyces pombe, cytokinesis is thought to be controlled by the daughter spindle-pole body (SPB) through a regulatory pathway named the septation initiation network (SIN). Here, we demonstrate that laser ablation of both, but not a single SPB, results in failure of cytokinesis. Ablation of only the daughter SPB often leads to activation of the SIN on the mother SPB and successful cytokinesis. Thus, either SPB can drive cytokinesis.

Cell Cycle Proteins↗
PubMed2004

Transcranial magnetic stimulation of the occipital pole interferes with verbal processing in blind subjects.

Recent neuroimaging studies in blind persons show that the occipital cortex, including the primary visual cortex (V1), is active during language-related and verbal-memory tasks. No studies, however, have identified a causal link between early visual cortex activity and successful performance on such tasks. We show here that repetitive transcranial magnetic stimulation (rTMS) of the occipital pole reduces accuracy on a verb-generation task in blind subjects, but not in sighted controls. An analysis of error types revealed that the most common error produced by rTMS was semantic; phonological errors and interference with motor execution or articulation were rare. Thus, in blind persons, a transient 'virtual lesion' of the left occipital cortex interferes with high-level verbal processing

Analysis of Variance↗
PubMed2005

Aurora-A - a guardian of poles.

The three human homologues of Aurora kinases (A, B and C) are essential for proper execution of various mitotic events and are important for maintaining genomic integrity. Aurora-A is mainly localized at spindle poles and the mitotic spindle during mitosis, where it regulates the functions of centrosomes, spindles and kinetochores required for proper mitotic progression. Recent studies have revealed that Aurora-A is frequently overexpressed in various cancer cells, indicating its involvement in tumorigenesis. What are the normal physiological roles of Aurora-A, how are these regulated and how might the enzyme function during tumorigenesis?

Aurora Kinases↗
PubMed2005

Polo kinase and progression through M phase in Drosophila: a perspective from the spindle poles.

Genes for the mitotic kinases Polo and Aurora A were first identified in Drosophila through screens of maternal effect lethal mutations for defects in spindle pole behaviour. These enzymes have been shown to be highly conserved and required for multiple functions in mitosis. Polo is stabilized at the centrosome by association with Hsp90. It is required for centrosome maturation on M-phase entry in order to recruit the gamma-tubulin ring complex and activate the abnormal spindle protein, Asp. These events facilitate the nucleation of minus ends of microtubules at the centrosome. The localization of Polo at the kinetochore and the mid-zone of the central spindle together with the phenotypes of polo mutants point to functions at the metaphase to anaphase transition and in cytokinesis. The latter are mediated, at least in part, through the Pavarotti kinesin-like motor protein and its conserved counterparts in other metazoans.

Animals↗
PubMed2001

Resorption of the lateral pole of the mandibular condyle in temporomandibular disc displacement.

OBJECTIVES: To assess the possible relationship between resorption of the superolateral pole of the mandible condyle (RSLC) and TMJ disk displacement. METHODS: Two hundred and seventeen TMJs in 138 patients were studied. Displacement of the disc, degree of displacement and disc configuration were assessed using MRI. RSLC was assessed from a transorbital radiograph. RESULTS: Seventy-two joints (37%) were considered to have RSLC. A significantly higher prevalence of RSLC was found in joints with disc displacement (goodness test of fit for chi-square, P<0.05). A significantly higher prevalence of RSLC was found in joints with advanced disc displacement and advanced disk deformation (Mann-Whitney U-test, P<0.01). CONCLUSIONS: RSLC appears more likely to occur in joints with advanced disc displacement.

Adolescent↗
PubMed2002

Cut1/separase C-terminus affects spindle pole body positioning in interphase of fission yeast: pointed nuclear formation.

BACKGROUND: The separase-securin complex is required for anaphase. Separase activated by securin destruction cleaves the cohesin subunit Scc1/Rad21 enriched in kinetochores. Fission yeast Cut1/separase resides in interphase cytoplasm and mobilizes to the spindle and the spindle pole bodies (SPBs) in mitosis, while Cut2/securin remains in the nucleus from interphase to metaphase, and temporarily locates at the short spindle. RESULTS: We here report a novel SPB-led dynamic nuclear movement in fission yeast, when the Cut1 C-terminal fragment is over-expressed. The tip of the pointed nucleus contained both SPB and centromeric DNA, and rapidly moved along the bundled cytoplasmic microtubules. The same pointed nucleus was produced when the human separase C-fragment was over-expressed. The pointed nuclear formation did not require the protease site of separase, but required the conserved C-terminus and a microtubule- and kinetochore-binding protein Mtc1/Alp14, a homologue of frog XMAP215 and budding yeast Stu2. The movement-inducing C-fragment should be cytoplasmic, as the pointed nucleus was abolished when the fragment contained the NLS (nuclear localization signal). CONCLUSIONS: Overproduced separase C-fragment abolishes correct SPB-positioning in interphase. Resulting pointed nuclear formation (alternatively called 'pigtail movement') requires cytoplasmic microtubules and Mtc1/Alp14.

Catalytic Domain↗
PubMed1997

Localization of the Escherichia coli cell division protein Ftsl (PBP3) to the division site and cell pole.

FtsI, also known as penicillin-binding protein 3, is a transpeptidase required for the synthesis of peptidoglycan in the division septum of the bacterium, Escherichia coli. FtsI has been estimated to be present at about 100 molecules per cell, well below the detection limit of immunoelectron microscopy. Here, we confirm the low abundance of FtsI and use immunofluorescence microscopy, a highly sensitive technique, to show that FtsI is localized to the division site during the later stages of cell growth. FtsI was also sometimes observed at the cell pole; polar localization was not anticipated and its significance is not known. We conclude (i) that immunofluorescence microscopy can be used to localize proteins whose abundance is as low as approximately 100 molecules per cell; and (ii) that spatial and temporal regulation of FtsI activity in septum formation is achieved, at least in part, by timed localization of the protein to the division site.

Alkaline Phosphatase↗
PubMed2002

Spc24 interacts with Mps2 and is required for chromosome segregation, but is not implicated in spindle pole body duplication.

Mps2 (monopolar spindle protein) is a coiled-coil protein found at the spindle pole body (SPB) and at the nuclear envelope that is required for insertion of the SPB into the nuclear envelope. We identified three proteins that interact with Mps2 in a two-hybrid screen: Bbp1, Ynl107w and Spc24. All three proteins contain coiled-coil motifs that appear to be required for their interaction with Mps2. In this work, we verified the Mps2-Spc24 interaction by co-immunoprecipitation in vivo and by the in vitro interaction of recombinant proteins. Previous two-hybrid screens with Spc24 as bait had identified Spc25 and Ndc80 as putative interacting partners, and we verified these interactions in vivo by purification of TAP-tagged derivatives of Spc24 and Ndc80. Finally, we found that spc24 thermosensitive mutants had a chromosome segregation defect, but no apparent defect in SPB duplication. These results are consistent with recently published data showing that Spc24, Spc25 and Ndc80 are peripheral kinetochore com-ponents required for chromosome segregation. The Mps2-Spc24 interaction may contribute to the localization of Spc24 and other kinetochore components to the inner plaque of the SPB.

Chromosome Segregation↗
PubMed2003

VirE2, a type IV secretion substrate, interacts with the VirD4 transfer protein at cell poles of Agrobacterium tumefaciens.

Agrobacterium tumefaciens transfers oncogenic DNA and effector proteins to plant cells during the course of infection. Substrate translocation across the bacterial cell envelope is mediated by a type IV secretion (TFS) system composed of the VirB proteins, as well as VirD4, a member of a large family of inner membrane proteins implicated in the coupling of DNA transfer intermediates to the secretion machine. In this study, we demonstrate with novel cytological screens - a two-hybrid (C2H) assay and bimolecular fluorescence complementation (BiFC) - and by immunoprecipitation of chemically cross-linked protein complexes that the VirE2 effector protein interacts directly with the VirD4 coupling protein at cell poles of A. tumefaciens. Analyses of truncation derivatives showed that VirE2 interacts via its C terminus with VirD4, and, further, an NH2-terminal membrane-spanning domain of VirD4 is dispensable for complex formation. VirE2 interacts with VirD4 independently of the virB-encoded transfer machine and T pilus, the putative periplasmic chaperones AcvB and VirJ, and the T-DNA transfer intermediate. Finally, VirE2 is recruited to polar-localized VirD4 as a complex with its stabilizing secretion chaperone VirE1, yet the effector-coupling protein interaction is not dependent on chaperone binding. Together, our findings establish for the first time that a protein substrate of a type IV secretion system is recruited to a member of the coupling protein superfamily.

Agrobacterium tumefaciens↗
PubMed2001

Transactivation of BARNASE under the AtLTP1 promoter affects the basal pole of the embryo and shoot development of the adult plant in Arabidopsis.

Genetically controlled expression of a toxin provides a tool to remove a specific structure and consequently study its role during a developmental process. The availability of many tissue-specific promoters is a good argument for the development of such a strategy in plants. We have developed a conditional system for targeted toxin expression and demonstrated its use for generating embryo phenotypes that can bring valuable information about signalling during embryogenesis. The BARNASE gene was expressed in the Arabidopsis embryo under the control of two promoters, one from the cyclin AtCYCB1 gene and one from the AtLTP1 gene (Lipid Transfer Protein 1). One-hundred percent seed abortion was obtained with the cyclin promoter. Surprisingly however, the embryos displayed a range of lethal phenotypes instead of a single arrested stage as expected from this promoter. We also show that BARNASE expression under the control of the AtLTP1 promoter affects the basal pole of the globular embryo. Together with reporter expression studies, this result suggests a role of the epidermis in controlling the development of the lower tier of the embryo. This defect was not embryo-lethal and we show that the seedlings displayed a severe shoot phenotype correlated to epidermal defects. Therefore, the epidermis does not play an active role during organogenesis in seedlings but is important for the postgermination development of a viable plant.

Arabidopsis↗
PubMed2003

Repeated variable prenatal stress alters pre- and postsynaptic gene expression in the rat frontal pole.

Exposure of pregnant women to stress during a critical period of fetal brain development is an environmental risk factor for developing schizophrenia in the adult offspring. We have applied a repeated variable stress paradigm to pregnant Sprague-Dawley rats during the last week of gestation coinciding with the second trimester in human brain development. Here we report our findings from a microarray analysis of the frontal pole of the prenatally stressed adult offspring and non-stressed adult controls complemented with measurement of plasma corticosterone levels following exposure to an acute stress. The direction of change of selected genes was confirmed by real time quantitative fluorescence PCR and in situ hybridization. The analysis revealed significant changes in genes associated with the NMDA receptor/postsynaptic density complex and the vesicle exocytosis machinery including NMDA receptor NR1 and NR2A subunits, densin-180, brain enriched guanylate kinase-associated protein, synaptosome-associated protein of 25 kDa, synaphin/complexin and vesicle-associated membrane protein 2/synaptobrevin 2. Interestingly, some of the changes in this animal preparation are analogous to changes observed in schizophrenic and bipolar patients. Our results suggest that application of a repeated variable prenatal stress paradigm during a critical period of fetal brain development reprograms the response of the hypothalamo-pituitary-adrenal axis to acute stress and results in gene expression changes that may have enduring effects on synaptic function in the offspring during adulthood.

Animals↗
PubMed2001

[Secondary ocular syphilis with chorioretinitis of the posterior pole - a case report].

BACKGROUND: Diagnosis of syphilis is often very difficult due to the absence of typical organ manifestation. In addition syphilis has the ability to imitate any ocular inflammation. This may result in misdiagnosis and delay of appropriate antimicrobial therapy. Up to now the first choice therapy is penicillin. CASE REPORT: We report about an otherwise healthy, 40 year-old-woman, who was referred to the Department of Ophthalmology, University of Tuebingen, due to an unclear loss of visual acuity (OD 0.1 and OS 0.4). The fundus examination disclosed focal chorioretinitis on the posterior pole, which was verified in fluorescein angiography. Secondary syphilis was diagnosed due to positive serological testing. Medical treatment consisted in Penicillin (i.m.) for 2 weeks and additional oral corticosteroids, which were tapered down slowly. After 3 months visual acuity had improved to 0.9 in the right and to 1.0 in the left eye. The former chorioretinitis regions showed only hyperpigmentation. CONCLUSIONS: Laboratory syphilitic testing should be performed in every uveitis.

Adult↗
PubMed1991

[Osteoma of the bulbus pole. Manifestations in relation to site and extent].

The authors followed the clinical course of two patients with osteoma of the posterior pole for a period of two years. A 60 year old male patient whose bone formation was confined to the episclera remained asymptomatic during the follow-up period. In contrast, the visual acuity of a 9 year old female patient with an osteoma of the choroid fell from 1.0 (20/20, 6/6) initially to 0.2 (20/100, 6/30) during the same two year follow-up interval. After reviewing the literature, the authors consider the pathophysiological prerequisites for ocular bone formation and discuss the differential diagnostic possibilities.

Child↗